Hydraulic work clamp for squaring shears



Oct. 16, 1956 P. G- PATER ET AL HYDRAULIC WORK CLAMP FOR SQUARING SHEARS Filed July 13, 1955 3 Sheets-Sheet 2 INVENTORS Paul GJaZer Kernel/z filthy/lei Howard RMaire BY "W M fir 7 Oct. 16, 1956 p G. PATER ETAL HYDRAULIC WORK CLAMP FOR SQUARING SHEARS 3 Sheets-Sheet 3 Filed July l3, 1955 rmew/ Paa s maW ,Y m mfl m m i2 0%? ii Patented views, 8 indicates the frame .of a conventional squaring shear, saidframehaving a ram 9 mounted thereon for 276682s vertical reciprocated lmovement between opposed side HYDRAULIC vWORK CLAMP FOR SQUA ING housings 10 and .11 and behind a hired front plate 12 SHEARS that is secured to the housings by .bolts 13. 'A work supporting bedplate 14 is also positioned upon the hous- Paul G. Pater Hamilton KennethE. Wagner Cmcmnatl a and Hmvard R. Manfe H} ton, Ohio, 2155i 5 mgs and 11 .and .has secured to its rearward end a stationary knife blade 15 which cooperates with the gfigffigii flgg gggy gg gfii g g gfig shear knifefblade .16 .movably' mounted onithe lower end 10 of. the ram 9. The .ramis reciprocated by pitmans.17-'1-7 Application y 1955; Serial 2 ,679 connected to an eccentric shaft '18 that is journaled in the housingslt) and .11, .said'fshaft having a gear 19 fixed (CL 164-5 thereto which meshes with a worm 20. The worm is driven by an electric motor 21 mounted on thehousing The present invention relates to squaring shears and 15 10 gh a pneumatic Clutch arrang ment generally is particularly directed to an hydraulic work clamp for indicated at 22 whichis electrically controlledbya foot said shears and to the system for actuating the clamp. S i c 3- Thus-When the'pnelimatic clutch 22 is up- It is common in the design of squaring shears toproerative the electric motor 21 Will reciprocate the ram 9 vide an hydraulic work clamp actuated by a pump that to bring the shear/knives 15 and -16 into cutting relation is mechanically driven from a moving part of the squarand return to sheal'fi Piece hf Work held IIPOI1 t h ing shear ram drive. As the work must be clamped be- Plate i t i forev the shearing operation the actuation of the work A row of-laterally spaced apart, hydraulically actuated clamp w t i ted to a ho t i iti l phase f th ram hold down devices 24 is" mounted on anddepend from operating cycle and as the feed stroke of the hold down fixed hp l e P Work P devices were relatively long their feed strokes were neces- 25 ated Oh y the q g- AS best Shown sarily at a fast rate of movement resulting in impact 3 0f the :drawings've'ach hold'down device 24 comprises shock of the devices on the work just prior to the time of it Verticaheyhnder 25 Seemed y bolts 2 the Plate 1 work clamping action. This was not objectionable when ,and housing -P which Slides therein; ialrlidywhieh relatively hard metal work sheets were cut on the squarv1'5 eonlleetedle a Work Contacting finger Projecting ing shears but when soft metal such as aluminum was -Ihf01lgh the P bottom of the 'cylhldeh Fluid to be cut thereon the impact shock of the hold down d p e i h d the actuating side 29 devices created objectionable marks and indentations on a Piston m? fluid-Pressure line 30 t is 0 m surface of the fi i h d work Inon'to all thehold'down devices; An expansile spring According to the present invention there is provided :3 su the finger is adapted to the a hold down actuating fluid pressure system whose OPerzfi 1 rm op r P j i111 Ihe absence of .ation' is entirely independent of the drive for the squarh o n r in pressu i the Common pp y lihe .ingshear ram, said system including automatic means t re r h .ll t that the TOW'Of Work for movement of the ram only after the work hold down hold downs 24 are single acting, "piston-cylinder devices has been fully operated and in full work clamping coni e h associatedfingers 28 tOWI'd the'wol'k dition. supported on ,thevbed plate-14 when fluid pressure great Another object of the invention is to provide a work enoughtoovercomeall thesprings 31 is introduced into hold down device for shears wherein the feeding speed the supply line 30 and thatsaid fingers willbe placed andhold down pressure of the clamping fingers are held under clamping action with said work when a relatively within certain limits calculated to preclude marring of higher head of pressure is caused to exist in thesaid the surfaces of soft materials vto be cut on the shears. supply line, the fingers being returnedto inoperative po- A further object of this invention is to provide an apsitions by the springs ,31, when the pressure in'the supply paratus of the aforedescribed character of extremely simline drops below the pressure exertedby'their combined pie construction which is positive in its action and which efiects. will automatically control both the feeding speed and With reference to Fig. 3 of the drawings a fluid pump clamping pressure ,of the work hold down fingers once .gencrallyindicated by the reference numeral 32 is prefthe apparatusis put in operation by a manual control. erably housed in acasing33 shown as mounted onithe .Still a further object of the invention is to provide a shear frame housing 11. Thispump is a single acting .novel pneumatically operated hydraulic pump for carrymaster cylinder assembly forsupplying fluid under presing out the foregoing objectives. sure to the supply line.3 0 offthe work hold down de- .Nuinerous other objects and advantages of this invenvices and comprises afirst chamber wall 34 and aco- ;tion' will become apparent from the following descripaxially positioned second chamber wall 35 preferably lion, reference being hadto the accompanying drawings .cast in and made integral with the casing 33. The' 'first which illustrate aIpresentl'y preferred embodiment of the chamber wall has a portion 36 projecting from one end invention, and wherein: of the second chamber wall 35 and has its opposite end 1 is effagmentehfufoflt elevahonal of a portion 37 extending into the central part of the'chamyp squaringShear 11t111z1ng-the work clamp mechabet formed by the wanes; A piston 38 is slidable withmsm and system of thls in the second chamber wall 35 and itself comprises} in Fig. 1.

Fig. 2 is a side elevational view of the shear illustrated lateral head 'pdmon aid an annular Skirt 40 extend ing from one side of head,porti on. fA plungerfil is fixed on the piston headcqaxially with the skirt porition and extends int'o and ,is slidable within the:,.first TchamberlWall-QM, the plunger and piston beingbiased Fig. 3 is an enlarged. section taken through the pneumatically. operated pumpfor the hydraulic work clamping system of this invention.

;Eig. 4 is a section taken on-line 4 4 of Fig. 3, and

V Fig. 5 is a diagrammatic view of; the work hold down .toward h ihP i P9 i. Shown i HE- .1 .3 F sysfm 7o expansile. spring. 42 surrounding. the portion 37 of the I ,Referring to the drawings wherein like characters of fi eh -m e e ihe f hg pnee ag s alat ra reference designatelike parts thr tn ghout the .seve ral wall ftfa of themaster cylir der an L L o he en againstan annular shoulder 44 formedaroundthe internal wall of the skirt portion 40 of the piston.

Conduit means such as a threaded opening 45 in the first chamber wall 34 and an associatedcoupling 46 conn'ects the first chamber of the master cylinder with the pressure'supply line 30 for the 'hold down devices, whilst the second chamber thereofis normally interconnected 'with the first chamber by means of a longitudinal passageway 47 in open communication with the first chamher through the pressure creating surface 48 of the plunger, the opposed end of the passageway 47 being connected to a diametrically extending passageway 49 formed in the plunger andwhich opens out into an' annular groove SOIformedin the periphery of an intermediate part of the plunger that is normally located within the second chamber. l

Apressure relief means 'is provided for the second chamber and comprises a stationary port 51 formed in the chamber wall 35 which is normally covered by the piston skirt portion 40 and out of registry with an annular groove 52 formed in a part of said skirt portion .adjacent the headfportion 39, a number of lateral holes 53 being formed in the skirt to connect the said groove with the interior of the second chamber. The reference numeral 54 represents a ball check valve immersed in oil ,55 contained in the bottom of the casing'33 and com- -municating with the first chamber by a pipe 56, said valve being adapted to preclude passage of pressure fluid from thesaid chamberbut admitting fluid to the chamber from'the reservoir to automatically replenish the hold down system when that becomes necessary through loss of oil from the system due to leakage, or the like. A

pressure relief valve 57 also immersed in oil 55 is con-- I ith reference to Fig. 5 which schematically 'illustrates the system for operating the hydraulic work clamp described hereinbefore the fluid pressure pipe 60 may be connected to a source of pneumatic pressure in a factory line. 63, said pipe 60 havinginterposed therein a pressure regulating valve 64, a volume control valve 65 and ajcontrol valve 66 operated by an electric solenoid 67. The supplyline 30 has a pressure switch 68 connected therein which is set to bridge the electric contacts 69 and 70 when a predetermined maximum pressure occurs in the said supply line 30. The contacts are in the electric circuit for controlling'the pneumatic clutch 22, said circuit including a clutch air valve coil 71.

' Operation iIn the operation of the system and with particular reference to Fig. 5 itwill be noted that the squaring 'shears. are put in condition for operation by closing a switch 72 which connects th'eelectric motor21 with electric power supply lines 73. Work to be cut on the shears is then placed on the'bed14 in the proper position thereon whereupon the foot switch 23 is actuated ,to energize the solenoid 67 which in turn operates the valve 66 to admit pressure fluid from the source 63 through line 60 to the power side 59 of the piston 38 in 'the master cylinder 32. The quantity and pressure spectively, slide are interconnected by -the longitudinal passageway 47 and the lateral passageway 49 formed in the plunger. Thus during the initial phase of movement of the piston and plunger a relatively large volume of pressure fluid will be introduced into the hold down supply line 30 to feed all the hold down fingers into contact with the work. The total volume of pressure fluid displaced by the piston and the plunger and discharged into the supply line 30 during this initial phase is substantially greater than the volume required to move all the fingers into contact with the work thus insuring a surplus of finger feeding pressure fluid for the system. As soon as the fingers contact the work the excess fluid displaced by the piston 38 is relieved at a relatively low pressure through pipe 58 and valve 57. With the fingers in contact with the work under the maximum pressure allowed in the supply line by relief valve 57 further travel of the piston and plunger in the master cylinder causes the adjacent edge of the end portion 37 on the first chamber wall 34 to cover up and close off the mouth of the lateral passageway 49 to thereby sever communication between the first and the second chambers. Simultaneously with the closing ofi of passageway 49 the annular groove 52 is brought into registry with the port 51 formed in the casing wall thereby interconnecting the second chamber with the reservoir to completely reduce internal pressure in the second chamber. As the piston and plunger continue to move through the final phase of their power stroke pressure on the fingers is intensified because fluid pressure introduced through pressure line 60 can act on piston 38 unrestricted by any counter- .forces to give full eflect of said fluid pressure on the plunger 41 in the closed space of the first chamber to thereby increase the clamping force exerted by the fingers upon the work preliminary to the cutting operation by the shear.

When the dwired work clamping pressure for the fingers has been reached the pressure switch 68 (Fig.5) will automatically close thus energizingthe'clutch air valve coil 71 which in turn actuates the clutch '22 to initiate the work shearing cycle of the ram 9. When the shearing cycle is complete a limit switch 74 is actuated to stop the sheai'and to deenergize the solenoid 67 which operates the control valve 66 to open the master cylinder side of the .pipe 60 to atmosphere thus relieving all pressure on the sure of the springs 31 in all of the hold down devices of the fluid admitted to the power side of the master cylinder is determined by the valves 65 and 64, respeccauses the piston and plunger to return to their inoperative positions shown in Fig. 3. During the first part of the return stroke the second chamber is filled with reserve oil .through the registered port 51 and groove 52 and the first chamber is filled with fluid returning by supply line 30'from the hold down devices. During the last phase of return travel of the piston and plunger the passageways 47 and 49 interconnect the two chambers, with the groove 52 and port 51 being moved out of registry so that both chambers are filled with fluid from the supply line 30, any loss of fluid due to leakage in the system being replenished through check valve 54 during the last phase of return movement of the piston and plunger.

Having described the features and functions of the invention it will be readily obvious that with our system the pressures and speeds of operation of the hold down i devices may be closely held within desired limits and are entirelyindependent of the operating cycle of the machine, initiation of the machine operation being subordinate to the completion of the work hold down operationand setting of the'actuated clamps on the work.

What is claimed is: i I 1. In' an hydraulic work clamp for squaring shears comprised of a number ofsingle acting, spring returned piston-cylinder work hold down devices each having its actuatingside connected to acommon fluid pressure supply line, a fluid pump having a firstchamber formed by a ylin an p n d m un c ing .with the s pp y line, and a second chamber formed by a cylinder and pistonnormally incommunication with said supply line, the said piston and plunger being connected together and the piston in the second chamber having aneflective area larger than the effective area of the plunger in the first chamber, ,a pressure relief valve for the second chamber, power means for moving the piston and the plunger, and valve means operative during continued movement of the piston and the plunger for cutting oif communication between the second chamber and the supply line.

2. In an hydraulic work clamp for squaring shears comprised of a number of single acting, spring returned piston-cylinder work hold down devices each having its actuating side connected to a common fluid pressure supply line, a fluid pump having a first chamber formed by a cylinder and piston and communicating with the supply line, and a second chamberformed by a cylinder and plunger normally incommunication .with said supply line, the said piston and plunger being connected together and the piston in the second chamber having an effective area larger than the effective area of the plunger in the first chamber, a pressure relief valve for the second chamber, a source of fluid under pressure, conduit means connecting the source to the power side of the piston in the second chamber, and normally inactive valve means made operative by the continued movement of the piston and the plunger for cutting off communication between the second chamber and the supply line.

3. In an hydraulic work clamp for squaring shears comprised of a number of single acting, spring returned piston-cylinder work hold down devices each having its actuating side connected to a common fluid pressure supply line, a single acting master cylinder for supplying actuating fluid through the supply line to the devices, said cylinder having a first chamber and a coaxially positioned second chamber having a relatively larger diameter than the first chamber, a piston arranged to slide in the second chamber, power means connected to said piston, a plunger fixed coaxially on the piston and extending into and slidable in the first chamber, conduit means connecting the first chamber to the supply line, a relief valve for the second chamber, a passageway formed in the plunger and normally interconnecting the first and second chambers, and fixed means in the cylinder for closing the passageway during continued movement of the piston and plunger by the power means.

4. In a hydraulic work clamp for squaring shears comprised of a number of single spring returned piston-cylinder work hold down devices, each having its actuating side connected to a common fluid pressure supply line, a single acting, master cylinder for supplying actuating fluid through the supply line to the devices, said cylinder having a first chamber and a coaxially positioned second chamber ha ing a relatively larger diameter than the said first chamber, a piston arranged to slide in the second chamber, cooperative pressure relief ports formed in the cylinder and in the piston and normally in inoperative, non-registered positions, power means connected to said piston, a plunger fixed coaxially on the piston and extending into and slidable in the first chamber, conduit means connecting the first chamber to the supply line, a passageway formed in the plunger and normally interconnecting the first and the second chambers, and fixed cut off means on the cylinder for closing the passageway simultaneously with registry of the cooperative pressure relief ports during continued movement of the piston and the plunger by the power means.

5. An hydraulic work clamp for squaring shears as set forth in claim 4 characterized by the fact that the power means is a source of fluid pressure in communication with the power side of the piston in the second chamber.

6. An hydraulic work clamp for squaring shears as set forth in claim 4 characterized by the fact that the fixed cut off means comprises the adjacent edge portion of the cylinder wall forming the first chamber in which the plunger slides, and the terminal end of said passageway that normally opens out from the plunger into the second chamber. l

7. In an hydraulic work clamp for squaring shears comprised of a number of single acting spring returned piston-cylinder work hold down devices, .each having its actuating side connected to a common fluid pressure supply line, a single acting, master cylinder for supplyingactuating fluid through the supply line to the devices, said cylinder having a first chamber wall and a coaxially-pqsitioned second chamber wall, said second chamber wall having a relatively larger diameter than said first chamber wall, a piston arranged to ,slide withinthe second chamber wall, said piston having a lateral head portion and an annular skirt extendingfromone sideof the head, a relief port formed in the chamber .wall and normally covered by the skirt portion, a port formed in the skirt normally out of registry with the portin'the chamber wall, power means connected to the side if thehead portion of the piston opposed to the skirt portion, a plunger fixed on the piston head coaxially with the skirt portion and extending into and slidable within the first chamber wall, conduit means connecting the first chamber to the supply line, a passageway formed longitudinally in the plunger and in open communication with the first chamber, a lateral passageway formed through an intermediate portion of the plunger in communication with the longitudinal passageway and normally in open communication with the second chamber, power means connected to the side of the head portion of the piston opposed to its skirt portion for moving the piston and plunger to simultaneously bring the relief ports into registry and cover the lateral passageway with the adjacent portion of the first chamber wall.

8. In the hydraulic work clamp for squaring shears as set forth in :claim 7 characterized by the fact that the second chamber is at all times connected to a pressure relief valve.

9. In the hydraulic work clamp for squaring shears as set forth in claim 7 characterized by the fact that the first chamber has a free intake, pressure ball check valve connected thereto at all times.

10. In a fluid pressure system for squaring shears the combination of a frame, a reciprocated ram on the frame, a work supporting bed positioned on the frame, power means for reciprocating the ram, a clutch interposed between the power means and the ram, 2. number of single acting, spring returned piston-cylinder work hold down devices on the frame above the bed and each having its actuating side connected to a common fluid pressure supply line, a fluid pump having a first chamber formed by a cylinder and plunger and communicating with the supply line, and a second chamber formed by a cylinder and piston and normally in communication with said supply line, the said piston and plunger being connected together and the piston in the second chamber having an effective pres sure area larger than the eflective pressure area of the plunger in the first chamber, a source of fluid pressure, a pressure line connecting the source to the power side of the piston in the second chamber, manually operable control means in the pressure line, a pressure responsive switch in the pressure supply line for the devices, means for operatively connecting the pressure responsive switch to the clutch to render the latter operative, a pressure relief valve for th second chamber set to operate at a relief pressure relatively less than the actuating pressure of the pressure responsive switch, and valve means operated by continued movement of the piston and the plunger for cutting oif communication between the second chamber and the supply line.

11. In a fluid pressure system for squaring shears the combination of a frame, a reciprocated ram on the frame, a work supporting bed positioned on the frame, power means for reciprocating the ram, a clutch interposed between thepower means and the ram, 3. number of single vacting, spring-returned piston-cylinder work hold down devices on the frame above the bed and each having its actuating side connected to a common fluid pressure supply line, a fluid pump having a first chamber wall anda coaxially positioned second chamber wall, said second chamber wall having a relatively larger diameter than said first chamber wall, a piston arranged to slide within the second chamber and having a lateral head portion and an annular skirt extending from one side of the head, a pair of relief ports formed one in the second cham ber wall and one in the piston skirt, said ports being axially separated by a distance equal to the pressure produc ing work stroke of the piston, a source of fluid under pressure, .a' connection between the source and the side of the piston head opposed to the skirt, an independent control means in said connection, a plunger fixed on the piston coaxially within theskirt portion and extending into and slidable within the first chamber wall, conduit means connecting the first chamber to the supply line, a

8 s V passageway formed longitudinally in the plunger and in open communication with the first chamber, a lateral passageway formed through an intermediate portion of the plunger and communicating with the longitudinal passageway, said. lateral passageway being normally in communication with the second chamber and closed by the first wall portion when the pair of relief ports are brought into registry, a pressure responsive switch in the supply line, means for operatively connecting the switch with the clutch to actuate the latter, and a pressure relief valve connected to the second chamber set to open at a pressure relatively less than the actuating pressure of the pressure responsive switch.

1,881,185 Hazelton Nov. 23, 1929 Seppman Jan. 1, 1952 

